Relief-valve for compound steam-pumps.



H. H. WESTINGHOUSE.

RELIEF VALVE FOR COMPOUND STEAM PUMPS.

APPLIOATION FILED sum. 16, 1907.

91 7,2 1 5 Patented Apr. 6, 1909.

wnnsssqs 1m: NORRIS PETERS ca., WAsHlNGTcN, n, c.

NIED STATES 7 OFIFIQO HENRY H. WESTINGHOUSE, OF NEW YORK, N. Y.,ASSIGNOR TO THE WESTINGHOUSE AIR BRAKE COMPANY, OF PITTSBURG,PENNSYLVANIA, A CORPORATION OF PENNSYL- VAN IA.

Specification of Letters latent.

Patented April 6, 1909.

Application filed. September 16, 1907. Serial No. 393,188.

To all whom it may concern:

Be it known that I, HENRY H. W ESTING- HOUSE, a citizen of the UnitedStates, residing at New York, in the county of New York and State of NewYork, have invented new and useful Improvements in Relief-Valves forCompound Steam-Pumps, of which the following is a specification.

This invention relates to compound steam pumps and more particularly tothe direct acting type in which the respective steam pistons aredirectly connected to the corresponding pistons in the compressorcylinders. In pumps of this character wherein the exhaust steam from thehigh pressure cylinder expands into the low pressure cylinder to actuateits piston, some diihculty has been experienced when the parts havebecome worn, on account of excessive leakage which occurs into thecylinder on the exhaust side of the high pressure steam piston, or whatamounts to the same thing, into the low pressure steam cylinders on thecorresponding side 01 its piston, whereby such an excessive pressureaccumulates as to greatly reduce the differential of pressures actingupon opposite sides of the piston and cause a very undesirable slowingdown of the pump. In pumps of this class, and particularly thoseemployed for compressing air as in an air brake system, it is highlydesirable that the pump should operate at a normally rapid rate of speedin order to eihciently compress air into the main reservoir under thehigh degree of pressure required to operate such a system, and it willbe observed that the slowing down of the pump, due to this objectionableleakage, serves to aggravate the difliculty, since it increases the timerequired for each stroke of the pistons and thereby lengthens the periodduring which this leakage may occur.

The principal object of my present invention is to maintain a desireddifferential of pressures acting upon opposite sides of the piston,whereby the pump may still continue to operate at a desired rate ofspeed, even in case of excessive leakage, and to this end it comprisesimproved valve means for automatically relieving such iston chamber orcylinder of the objectionable pressure due to such leakage.

Another feature of my improvement comprises means whereby the reliefvalve mechanism operates under varying conditions of steam or boilerpressure to maintain a desired differential.

In the accompanying drawing the figure shows, in vertical section, acompound steam pump with one form of my improvement applied thereto.

According to this construction the air pump shown is of the type whereinthe high pressure steam cylinder 1 contains piston 2 connected by rod 3with the piston t in the low pressure air cylinder 11, and the lowpressure steam piston 5 in cylinder 6 is con nected by rod 7 with thepiston 8 of the high pressure air cylinder 9, the pump valve mechanismin casing 10 being controlled by the reversing rod 12 actuated by themovement of the high pressure steam piston. My invention is not,however, restricted to any particular form of compound pump, since itmay be applied to any ordinary or preferred pump construction and havingany suitable design of valve mechanism.

The specific form of my improvement shown in the drawing comprises arelief valve 13, which is subject on its face to the pressure in chamber19, communicating by passage or pipe 18 with one end of the low pressuresteam cylinder 6, and operating to control an outlet or discharge port17. The valve may be loaded by a spring 15, and in order that the loadtending to hold the valve to its seat may be automatically adjusted tovarying conditions and different degrees of steam pressure, the valve ispreferably provided with a reduced extension 14, which is subject on itsrear side to the live steam or boiler pressure admitted through passage16. This provides diflerential areas exposed to steam pressure uponopposite sides of the relief valve, and the same is normally held closedby the live steam pressure acting on the extension 14, and the pressureof spring 15, which is made of a suitable strength to hold the valveclosed under the desired conditions, but to permit the valve to open andrelieve the pressure in the steam cylinder when the same "increasesabove a desired maximum degree. A duplicate valve device 18, 14, 15 and19 may be connected by passage or pipe 18 with the opposite end of thesteam cylinder.

It will now be apparent that with my improvement, if there is anexcessive leakage of steam to the exhaust side of the high pressurepiston, or to the corresponding side of the low pressure piston, causingan undesirable increase in the pressure acting on the face of the reliefvalve, said valve will be raised from its seat and discharge such excesspressure through the outlet port 17. In this manner the desireddifferential in the steam pressures will be maintained and the pumppistons will move at the required speed and operate to efficientlycompress the air or other fluid acted upon. It is also evident that,should there be any change in the conditions of the boiler or live steampressure, the load on the relief valve will be automatioally adjusted toa corresponding degree, so that the same desired differential of steampressures acting upon the engine pistons will be maintained regardlessof varying conditions of the live steam pressure.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is i 1. The combination with a compound steampump having high and low pressure cylinders and pistons, of means forrelieving the pressure accumulating by leakage upon either side of thesaid pistons.

2. The combination with a compound steam pump having high and lowpressure cylinders and pistons, of a relief valve for dischargingpressure accumulating by leak age to one side of the low pressurepiston.

3. The combination with a compound steam pump having high and lowpressure cylinders and pistons, of a relief valve-device for limitingthe pressure upon either side of the low pressure piston.

4. The combination with a compound steam pump having high and lowpressure cylinders and pistons, of a loaded relief valve governed byfluid pressure for limiting the pressure upon one side of the lowpressure piston.

5. The combination with a compound steam pump having high and lowpressure cylinders and pistons, of a relief valve device governed bylive steam pressure for limiting the pressure upon either side of thelow pres sure piston.

6. The combination with a compound steam pump having high and lowpressure cylinders and pistons, of a relief valve device governed bylive steam pressure for limiting the pressure upon either side of thelow pressure piston to a predetermined degree.

In testimony whereof I have hereunto set my hand.

HENRY H. WESTINGHOUSE. Witnesses:

ROBERT MoLEoD JACKSON, E. A. WRIGHT.

